Algebra word problem

[jamjam]

The balance in Will's mastercard account grew 2%, to $870, in one month. What was his balance at the beginning of the month?
I'm not sure if I am supposed to divide $870 by 2% to get $435 as the balance at the beginning of the month. HELP!

 

[TchrWill]

B(1.02) = 870

 

[jamjam]

Thanks for the hint